The invention relates to a formation core sample holder assembly and a core testing method. In the oil and gas production industry it is common practice to take, when an exploration or production well is being drilled, one or more cylindrical core samples of hydrocarbon containing or other formation and to subsequently perform one or more tests with this core sample in a laboratory.
During these tests the sample is arranged in a pressurized sample holder assembly, in which the temperature and pressure are substantially similar to the ambient pressure and temperature within the hydrocarbon containing or other formation from which the sample has been taken, and a treating, completion and/or stimulation fluid is injected into the sample to determine an optimum composition of the treating, completion and/or stimulation fluid and/or an optimum injection regime.
A known core holder assembly in which the core sample is contained within an elastomeric sleeve is known as the Hassler core holder and is described in U.S. Pat. No. 2,345,935 issued to G. L. Hassler. Other core holder assemblies equipped with elastomeric sleeves are known from U.S. Pat. No. 4,563,726 issued to Core Laboratories Inc. and from U.S. Pat. No. 5,698,772 issued to Institut Francais du Petrole.
A problem of the known core sample holder assemblies is that they are not suitable to maintain the core sample at elevated temperature and pressure while electromagnetic radiation is transmitted through the core sample to monitor the fluid migration within the core sample.
A further problem of the known core sample holder assemblies is that they are provided with elastomeric sleeves which are not suitable for use at high temperatures of more than 300 degrees Celsius and/or are susceptible to fatigue, thermal break down and/or material degradation.
A further problem of the known core holder assemblies is that they are provided with elastomeric sleeves, which are not suitable to exposure to certain chemicals, such as hydrogen sulphide and carbon dioxide.
It is an object of the present invention to provide a core holder assembly and core testing method, which provide a solution to these problems.